The trillions of bacteria that call the intestines home collectively make up the gut microbiome. Bacteria in the gut do much more than digest food and break it down into nutrients; they are involved in many biological functions including metabolic processes and regulating aspects of our immune system. Researchers are learning that these tiny creatures are important in the general maintenance of good health and are incredibly sensitive to change. Disruption of gut bacteria has been implicated in a host of health conditions including diabetes, obesity and autoimmune diseases like inflammatory bowel disorder and multiple sclerosis (MS). Studies have shown that certain strains of bacteria are elevated in individuals with MS but not in healthy individuals. We will be hearing more about the role the gut microbiome plays in the development, prevention, and treatment of MS in the coming years.
Already, the gut microbiome was an area of great interest at the #MSParis2017 conference this year. Here are highlights of the research discussed in the talks of Dr. Hartmut Wekerle and Dr. Helen Tremlett.
Dr. Hartmut Wekerle: The composition of the gut microbiome may be a trigger for MS
Dr. Hartmut Wekerle, an Emeritus Director at the Max Planck Institute of Neurobiology in Munich, was interested in the connections between the gut microbiome and brain and how these interactions may trigger MS. Dr. Wekerle used a mouse model of MS to test the connections between the two in what he called the “Munich twin trial.” Dr. Wekerle initially compared the gut composition of 34 pairs of human identical (or monozygotic) twins in which one twin had MS and the other twin was not impacted by the disease. He found an increase in a bacterial species called Akkermansia, a species that is currently being studied by other researchers for its effects on metabolism, obesity, diabetes and inflammation. Dr. Wekerle and his research team then transplanted fecal matter from the healthy twin and the twin with MS into healthy mice known to be susceptible to MS. The fecal matter from the healthy twin induced MS in 30% of these mice, whereas MS developed in 60% of the mice that received fecal transplant from a twin with MS. Dr. Wekerle’s team also measured the microbial profiles of the mice, producing two important findings in the mice with a fecal transplant from a twin with MS. The mice showed decreases in the normal levels of an organism in the gut called Sutterella, which has been previously shown to regulate the immune response. They also showed a decrease in normal levels of interleukin 10, an anti-inflammatory molecule. The work performed by Dr. Wekerle and his team suggests that the components of the microbiome contribute to the development of MS. This work was recently published in the renowned journal Proceedings of the National Academy of Sciences.
Dr. Helen Tremlett: Triggers and facilitators of MS in children with MS
Dr. Helen Tremlett’s (University of British Columbia) research interest lies in the role the gut may play in triggering or facilitating MS. In a group of kids with MS, Dr. Tremlett set out to explore two primary questions: (1) Do the gut micro-organisms that make up the microbiome differ in kids with pediatric MS from kids without MS? and (2) Is the composition of the microbiome in the gut associated with future relapse risk in pediatric MS?
A population of pediatric MS patients affords researchers the opportunity to study the disease process at very early stages of MS. Dr. Tremlett measured the composition of the gut microbiome in 15 children with MS and compared it with nine children without MS. Her research team aimed to discover any differences in the relationship between the developing gut microbiota and certain cells of the immune system known to be markers. Dr. Tremlett and her team discovered correlations between the diversity of gut microbiota and the presence of markers from the immune system in children without MS. However, these correlations were not identified in children who have MS suggesting that the relationship between the gut microbiome and immune system can impact the development of MS.
In another study, Dr. Tremlett examined whether the relapse rate in pediatric MS was associated with alterations in the gut microbiome. The research team discovered that depletion of a bacteria called Fusobacteria in children with MS was associated an earlier relapse compared with children who had this bacterium. Interestingly, Fuscobacteria was previously correlated with immune system markers in children without MS but not those with MS.
The gut microbiome influences the risk of developing MS as well as progression in MS-and it may be possible to modify it. But first many questions remain to be answered. What key microorganisms in the gut regulate the immune system? What mechanism(s) allows for the associations between the gut and MS? Researchers around the world are eagerly pursuing the needed data.
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